1. Field of the Invention
The present invention relates to pet litter boxes for pets such as cats kept indoors, and more specifically relates to a pet litter box that can be maintained cleanly and easily by effectively utilizing a liquid-absorbing sheet.
2. Related Art
A plastic container, in which litter composed of granular materials (so called “cat litter”) is placed, has been generally used as a litter box for pets such as cats and dogs kept indoors. The granular materials include mineral materials such as zeolite, river sand, bentonite that becomes hard when it absorbs liquid like urine, and cellulose grains that are formed by hardening crushed pulp. A pet such as a cat enters the litter box, and excretes urine or feces on the litter. The owner of the pet removes the litter soiled with urine or feces from the container along with feces using a scoop, and then adds new litter in accordance with the amount of the litter removed.
However, since pets like cats have a habit of mixing litter with their paws after excretion, the amount of the litter soiled with urine or feces is increased and the soiled litter is scattered. Thus, it is difficult to remove only the soiled portion of the litter.
On the other hand, zeolite and river sand do not absorb urine, and bentonite and cellulose grains absorb urine to some extent but cannot absorb it completely. On this account, urine passes through the litter and tends to be retained at the bottom of the container. It takes a long time for this urine to evaporate and urine impurities adsorbed on the litter tend to cause urine odor to emanate. Therefore, the owner must keep the litter box clean by changing all of the litter in the container once a week to two weeks, washing and drying the container, and then placing new litter in the container.
Moreover, discarding litter every time an animal excretes and replacing all the litter once a week to two weeks increase the amount of litter used. When a granular mineral such as zeolite is used as the litter, it is difficult to be discarded as waste because it is non-combustible.
To solve the problems mentioned above, pet litter boxes disclosed in Japanese Utility Model Registration No. 3088484 (Patent Document 1) and Japanese Unexamined Patent Application Publication No. 10-229768 (Patent Document 2) were developed, for example. In the pet litter box disclosed in Patent Document 1, granular materials are placed in a container having a pass partition plate with a streaky water-dripping structure at the bottom. A loadable tray, in which a liquid-absorbing sheet is placed, is disposed below the bottom pass partition plate. Urine passes through the granular materials and through the bottom part of the container, and it is then absorbed by the liquid-absorbing sheet. Also, in the pet litter box disclosed in Patent Document 2, water resistant granular materials are placed in a container having a bottom sheet with a liquid-passing structure. A liquid-absorbing sheet supported by a support is disposed below the bottom part of the container in close contact with the bottom sheet. Urine passes through the water resistant granular materials and through the bottom part of the container, and then is absorbed by the liquid-absorbing sheet. In this way, urine does not remain in the container, and the litter box may be cleaned by putting antimicrobial agents and super absorbent polymers into the liquid-absorbing sheet to prevent rot or bad smell and simply changing the liquid-absorbing sheet once a week. The entirety of the granular material is replaced once a month to once every two months. This readily reduces the amount of waste without much effort.
However, pets such as cats usually urinate at one area on the liquid absorbing sheet, leaving only that area soiled. Thus, the liquid-absorbing sheet is sometimes reused by turning it around so that unsoiled parts of the liquid-absorbing sheet will be at the area at which the pet urinates (according to the inventors' research, among pet owners who use this type of pet litter box, 37% responded that they reuse the liquid-absorbing sheet by turning it around).
To turn around the liquid-absorbing sheet disposed in the tray, it is necessary to remove the liquid-absorbing sheet from the tray and turn it around. However, the liquid-absorbing sheet will be heavy after absorbing urine and will be lost stiffness, which makes it difficult to handle the liquid-absorbing sheet and requires effort to remove the liquid-absorbing sheet and re-disposing it after changing its front-back direction. In the worst case, this may cause inconvenience because the liquid-absorbing sheet fails to absorb urine due to a turn-up of the liquid-absorbing sheet while it is disposed in the tray. Also, it is unsanitary because hands become soiled while handling the liquid-absorbing sheet.